Tip of the iceberg

Meaning

A small visible part of a much larger issue.

Usage

Warns about hidden problems.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

Icebergs have most mass beneath water.

Longstanding maritime metaphor.